Introduction
As our knowledge of chemistry and reactions grows, everyday processes such as baking evolve as well. One of the most interesting aspects of baking is the concept of reactions taking place in the dough, causing breads and batters to rise, creating a variety of different textures. Recipes have developed as our understanding increases in order to achieve calculated textures and reactions for the perfect baked good. By studying some of the leavening methods and ingredients used, I plan to determine how some of these reactions came to be.
Beginning with the simplest of leavening techniques, some recipes rise without any leavening agent at all. Creaming is known as the process in which sugar and eggs are beaten together with a fat, incorporating a low-density ingredient to batters and doughs. The light, fluffy texture of the beaten eggs creates enough air in the mixture that while baking, this air bubbles will keep the dough from sinking and create a lighter texture. The egg has a great number of essential purposes in a dough. Egg whites both stabilize the dough and help it to foam up.1 In addition, batters are more often then not combinations of immiscible ingredients, and egg yolks serve as emulsifiers2, which keep doughs from separating out. Unlike egg, a standard ingredient, types of fats used in creaming vary. Between butter and shortening, each has its advantages and disadvantages. Butter for instance has a lower melting point than shortening, causing cookie doughs to spread out more quickly while baking. This spreading prevents dough from rising, causing a crunchier texture, however butter provides the dough with a better taste. Butter's structure also yields large bubbles that are prone to escaping during baking. Shortening on the other hand, while containing a slightly bitter taste, is a superior ingredient with texture in consideration. With a much higher melting point, the dough does not spread nearly as much in the oven, and nitrogen bubbles produced are less likely to escape allowing more rising. Shortening is also an extra emulsifier. Finally, granulated sugar's purpose, along with taste, is to break up the fat, creating air pockets. These air pockets expand with heat and contribute to the soft, low density texture of baked goods.
Another method of leavening cookies and breads is the use of yeast. Yeast, a live ingredient is a unicellular fungi which helps breads and batters to rise through carbon dioxide production. Yeast can obtain energy either with oxygen or with glucose. In doughs and such, with a lack of oxygen, yeast cells produce energy anaerobically in a process called fermentation.3 In this reaction, yeast cells take glucose and convert it to ethanol and carbon dioxide:
C 6 H12 O6→ C2 H5 OH + CO2
Fermentation is used for both alcohol production and baking. The ethanol is a primary reactant for alcohol, however in doughs, it evaporates when heated. The important ingredient in baking, the carbon dioxide is essential. When heated, the carbon dioxide expands, creating air bubbles that allow the batter to rise. The yeast itself cannot survive at a temperature greater than about 150 degrees F, so it is also killed during the baking.
The final method of leavening baked goods is through the use of chemicals. Baking powder and baking soda are currently the most popular leavening agents. Baking soda, composed of pure sodium bicarbonate is very simple, yet it has its draw backs. Baking soda is a basic chemical so it reacts with the slightly acidic ingredients in a batter such as milk, honey, chocolate, citrus, or yogurt. This reaction produces the all important carbon dioxide which expands in the oven:
2NaHCO3→ Na2CO3 + H2O + CO2
However, since the acid/base reaction occurs as soon as ingredients are mixed together, an immediate reaction occurs. If a dough containing baking soda is not immediately baked, then too much carbon dioxide with be released, causing too much expansion. If too much carbon dioxide gas rises, then it will simply escape and the dough will deflate and sink, rendering all leavening useless. For this reason, baking soda can be inconvenient with a time constraint. In addition, baking soda has a slightly bitter taste. Baking powder is another chemical compound that was created to eliminate some of the constraints of baking soda. Baking powder was originally invented in 1846 by a British chemist who sought to avoid the use of egg or yeast in baked goods. Baking powder is a combination of sodium bicarbonate, cream of tartar (acid ingredient), and corn starch at a ratio of 2:1:1. While baking soda is basic, baking powder is neutral because it contains both the base and the acid. The purpose of the corn starch is to absorb excess moisture.4 In addition, baking powder is almost always sold as “double acting”, meaning that some carbon dioxide gas reacts when dough is mixed, but some reacts with the impetus of heat. This double acting feature is achieved by including very slow reacting acids for the first part, and heat sensitive reactants for the second part to keep the entire reaction in check. This allows dough to sit for a period of time before baking without adverse effects. It also has a more neutral taste to it. Though baking powder is generally more convenient in use and taste, recipes vary between baking powder and baking soda primarily due to surrounding ingredients required.
Procedure:
For my project, my goal was to determine and distinguish the function of each ingredient in baking powder. I created my own baking powder with varying ratios of the three ingredients: baking soda, corn starch, and cream of tartar. I then applied each variation of baking powder into one standard cookie recipe to observe the effects. I changed the baking soda ratios in the hopes of looking at the differences in batches of cookies and determining what each ingredient's role is.
Part 1: Start by mixing the 4 versions of baking powder with varying ratios of sodium bicarbonate, cream of tartar, and corn starch
1. In a separate container, mix same 3 ingredients at a ratio of 2:1:1 (standard baking powder recipe)
2. Repeat step 2 following a 1:2:1 ratio
3. Repeat step 2 again now following a 1:1:2 ratio
Part 2: incorporate each mixture of baking powder into the same cookie recipe
1. Follow the recipe below for cookies
1 and 1/4 cups all-purpose flour
1 large egg
3/4 cup sugar
3/4 cup brown sugar
1 cup melted butter
1 teaspoon baking powder
1 teaspoon vanilla extract
1/2 teaspoon salt
2 cups of semisweet chocolate chips
Preheat the oven to 375 degrees.
Use a large bowl and mix in white sugar, brown sugar, vanilla extract, butter and egg. Mix until an even creamy liquid (use electric mixer). Stir in flour, baking powder, and salt.
Gently stir in chocolate chips.
Take cookie dough and place on cookie sheets (roughly 1 tablespoon per cookie.) Leave about 2 inches of space between every drop in the case of spreading while baking.
Put the baking sheet with your cookies into the oven and bake them for 8 to 10 minutes. When they get light brown they are done.
2. Make 3 different batches of cookies, each time substituting a different baking powder mixture from Part I
3. Immediately bake each batch as soon as dough is finished, bake each batch of cookies for exactly 10 minutes. Make and write down observations about amounts of rising while cookies bake
4. Allow cookies to cool on cooling rack when finished baking
Part 3: Measuring outcomes
1. For each batch of cookies measure five different cookies for the following qualities
2. diameter (measure to the nearest millimeter)
3. weight
4. volume- Perform water displacement test. Before submerging cookies in water, carefully wrap cookies securely in 2-3 layers of saran wrap to avoid absorption. Be careful while wrapping cookies not to compress them and decrease the volume)
5. using the weight and volume calculate the density
6. calculate the averages of the five cookies from each of the three batches and compare data
Results (averaged from 5):
Type #1 (2:1:1 ratio of NaHCO3: cream of tartar: cornstarch)
mass: 16.33g
volume: 18.2 ml
density: .94 g/ml
diameter: 5.66 cm
Type #2 (1:2:1 ratio of NaHCO3: cream of tartar: cornstarch)
mass: 16.79 g
volume: 14 ml
density: 1.23 g/ml
diameter: 5.62 cm
Type #3 (1:1:2 ratio of NaHCO3: cream of tartar: cornstarch)
mass: 17.82 g
volume: 20 ml
density: .89 g/ml
diameter: 6.1 cm
Conclusions
Unfortunately, results from my experimentation on different types of baking powder were not as clear and conclusive as I had hoped. However, there were some interesting observations. Firstly, as a personal record, all three batches had a far better texture from any of my previous attempts outside of the experiment. There was far less spreading (mine normally pancake) and the cookies were soft as opposed to crispy. I will note however, that this recipe was not the usual recipe I use because I needed to incorporate baking powder instead of baking soda. I found (in concordance with others who have tasted both) that the original recipe with baking soda tastes the best. Though this information is not part of the experiment, it was an interesting observation.
Within the experiment, the 1st and 2nd batches were a little more similar than the 3rd batch of cookies (1:1:2 ratio) which had a different texture. While the other two batches were thick and hardly spread while baking, the third batch spread more. This was observed both by its crispier, browner edges, and also by its harder, crumblier texture. This was also apparent in the diameter data. Taste testers' answers were fairly varied as well, however some of the common threads were that #1 was very sweet and thick, #2 was crumblier and less sweet, and #3 was the least sweet and drier. It can be concluded that the favored batch among most test tasters was #1, which is in fact standard recipe for cookies.
As our knowledge of chemistry and reactions grows, everyday processes such as baking evolve as well. One of the most interesting aspects of baking is the concept of reactions taking place in the dough, causing breads and batters to rise, creating a variety of different textures. Recipes have developed as our understanding increases in order to achieve calculated textures and reactions for the perfect baked good. By studying some of the leavening methods and ingredients used, I plan to determine how some of these reactions came to be.
Beginning with the simplest of leavening techniques, some recipes rise without any leavening agent at all. Creaming is known as the process in which sugar and eggs are beaten together with a fat, incorporating a low-density ingredient to batters and doughs. The light, fluffy texture of the beaten eggs creates enough air in the mixture that while baking, this air bubbles will keep the dough from sinking and create a lighter texture. The egg has a great number of essential purposes in a dough. Egg whites both stabilize the dough and help it to foam up.1 In addition, batters are more often then not combinations of immiscible ingredients, and egg yolks serve as emulsifiers2, which keep doughs from separating out. Unlike egg, a standard ingredient, types of fats used in creaming vary. Between butter and shortening, each has its advantages and disadvantages. Butter for instance has a lower melting point than shortening, causing cookie doughs to spread out more quickly while baking. This spreading prevents dough from rising, causing a crunchier texture, however butter provides the dough with a better taste. Butter's structure also yields large bubbles that are prone to escaping during baking. Shortening on the other hand, while containing a slightly bitter taste, is a superior ingredient with texture in consideration. With a much higher melting point, the dough does not spread nearly as much in the oven, and nitrogen bubbles produced are less likely to escape allowing more rising. Shortening is also an extra emulsifier. Finally, granulated sugar's purpose, along with taste, is to break up the fat, creating air pockets. These air pockets expand with heat and contribute to the soft, low density texture of baked goods.
Another method of leavening cookies and breads is the use of yeast. Yeast, a live ingredient is a unicellular fungi which helps breads and batters to rise through carbon dioxide production. Yeast can obtain energy either with oxygen or with glucose. In doughs and such, with a lack of oxygen, yeast cells produce energy anaerobically in a process called fermentation.3 In this reaction, yeast cells take glucose and convert it to ethanol and carbon dioxide:
C 6 H12 O6→ C2 H5 OH + CO2
Fermentation is used for both alcohol production and baking. The ethanol is a primary reactant for alcohol, however in doughs, it evaporates when heated. The important ingredient in baking, the carbon dioxide is essential. When heated, the carbon dioxide expands, creating air bubbles that allow the batter to rise. The yeast itself cannot survive at a temperature greater than about 150 degrees F, so it is also killed during the baking.
The final method of leavening baked goods is through the use of chemicals. Baking powder and baking soda are currently the most popular leavening agents. Baking soda, composed of pure sodium bicarbonate is very simple, yet it has its draw backs. Baking soda is a basic chemical so it reacts with the slightly acidic ingredients in a batter such as milk, honey, chocolate, citrus, or yogurt. This reaction produces the all important carbon dioxide which expands in the oven:
2NaHCO3→ Na2CO3 + H2O + CO2
However, since the acid/base reaction occurs as soon as ingredients are mixed together, an immediate reaction occurs. If a dough containing baking soda is not immediately baked, then too much carbon dioxide with be released, causing too much expansion. If too much carbon dioxide gas rises, then it will simply escape and the dough will deflate and sink, rendering all leavening useless. For this reason, baking soda can be inconvenient with a time constraint. In addition, baking soda has a slightly bitter taste. Baking powder is another chemical compound that was created to eliminate some of the constraints of baking soda. Baking powder was originally invented in 1846 by a British chemist who sought to avoid the use of egg or yeast in baked goods. Baking powder is a combination of sodium bicarbonate, cream of tartar (acid ingredient), and corn starch at a ratio of 2:1:1. While baking soda is basic, baking powder is neutral because it contains both the base and the acid. The purpose of the corn starch is to absorb excess moisture.4 In addition, baking powder is almost always sold as “double acting”, meaning that some carbon dioxide gas reacts when dough is mixed, but some reacts with the impetus of heat. This double acting feature is achieved by including very slow reacting acids for the first part, and heat sensitive reactants for the second part to keep the entire reaction in check. This allows dough to sit for a period of time before baking without adverse effects. It also has a more neutral taste to it. Though baking powder is generally more convenient in use and taste, recipes vary between baking powder and baking soda primarily due to surrounding ingredients required.
Procedure:
For my project, my goal was to determine and distinguish the function of each ingredient in baking powder. I created my own baking powder with varying ratios of the three ingredients: baking soda, corn starch, and cream of tartar. I then applied each variation of baking powder into one standard cookie recipe to observe the effects. I changed the baking soda ratios in the hopes of looking at the differences in batches of cookies and determining what each ingredient's role is.
Part 1: Start by mixing the 4 versions of baking powder with varying ratios of sodium bicarbonate, cream of tartar, and corn starch
1. In a separate container, mix same 3 ingredients at a ratio of 2:1:1 (standard baking powder recipe)
2. Repeat step 2 following a 1:2:1 ratio
3. Repeat step 2 again now following a 1:1:2 ratio
Part 2: incorporate each mixture of baking powder into the same cookie recipe
1. Follow the recipe below for cookies
1 and 1/4 cups all-purpose flour
1 large egg
3/4 cup sugar
3/4 cup brown sugar
1 cup melted butter
1 teaspoon baking powder
1 teaspoon vanilla extract
1/2 teaspoon salt
2 cups of semisweet chocolate chips
Preheat the oven to 375 degrees.
Use a large bowl and mix in white sugar, brown sugar, vanilla extract, butter and egg. Mix until an even creamy liquid (use electric mixer). Stir in flour, baking powder, and salt.
Gently stir in chocolate chips.
Take cookie dough and place on cookie sheets (roughly 1 tablespoon per cookie.) Leave about 2 inches of space between every drop in the case of spreading while baking.
Put the baking sheet with your cookies into the oven and bake them for 8 to 10 minutes. When they get light brown they are done.
2. Make 3 different batches of cookies, each time substituting a different baking powder mixture from Part I
3. Immediately bake each batch as soon as dough is finished, bake each batch of cookies for exactly 10 minutes. Make and write down observations about amounts of rising while cookies bake
4. Allow cookies to cool on cooling rack when finished baking
Part 3: Measuring outcomes
1. For each batch of cookies measure five different cookies for the following qualities
2. diameter (measure to the nearest millimeter)
3. weight
4. volume- Perform water displacement test. Before submerging cookies in water, carefully wrap cookies securely in 2-3 layers of saran wrap to avoid absorption. Be careful while wrapping cookies not to compress them and decrease the volume)
5. using the weight and volume calculate the density
6. calculate the averages of the five cookies from each of the three batches and compare data
Results (averaged from 5):
Type #1 (2:1:1 ratio of NaHCO3: cream of tartar: cornstarch)
mass: 16.33g
volume: 18.2 ml
density: .94 g/ml
diameter: 5.66 cm
Type #2 (1:2:1 ratio of NaHCO3: cream of tartar: cornstarch)
mass: 16.79 g
volume: 14 ml
density: 1.23 g/ml
diameter: 5.62 cm
Type #3 (1:1:2 ratio of NaHCO3: cream of tartar: cornstarch)
mass: 17.82 g
volume: 20 ml
density: .89 g/ml
diameter: 6.1 cm
Conclusions
Unfortunately, results from my experimentation on different types of baking powder were not as clear and conclusive as I had hoped. However, there were some interesting observations. Firstly, as a personal record, all three batches had a far better texture from any of my previous attempts outside of the experiment. There was far less spreading (mine normally pancake) and the cookies were soft as opposed to crispy. I will note however, that this recipe was not the usual recipe I use because I needed to incorporate baking powder instead of baking soda. I found (in concordance with others who have tasted both) that the original recipe with baking soda tastes the best. Though this information is not part of the experiment, it was an interesting observation.
Within the experiment, the 1st and 2nd batches were a little more similar than the 3rd batch of cookies (1:1:2 ratio) which had a different texture. While the other two batches were thick and hardly spread while baking, the third batch spread more. This was observed both by its crispier, browner edges, and also by its harder, crumblier texture. This was also apparent in the diameter data. Taste testers' answers were fairly varied as well, however some of the common threads were that #1 was very sweet and thick, #2 was crumblier and less sweet, and #3 was the least sweet and drier. It can be concluded that the favored batch among most test tasters was #1, which is in fact standard recipe for cookies.
References:
1. American Egg Board. "Eggs." Baking Management. 1 May 2005. Web. 2 May 2010. <http://baking- management.com/rd_applications/bm_imp_8806/index.html?imw=Y>.
2. Brandt, Laura, ed. Food Product Design. 1 Feb. 1996. Web. 2 May 2010. <http://www.foodproductdesign.com/articles/1996/02/emulsifiers-in-baked-goods.aspx>.
3. Yeast." Chemistry Daily. 4 Jan. 2007. Web. 2 May 2010. <http://www.chemistrydaily.com/chemistry/Yeast>.
4. Helmenstine, Ph D, Anne Marie. "What Is the Difference Between Baking Soda & Baking Powder." About.com: Chemistry. Web. 2 May 2010. <http://chemistry.about.com/cs/foodchemistry/f/blbaking.htm>.